System and methods for establishing a communication session between an implantable medical device and an external device

ABSTRACT

A method is provided for establishing a communication session with an implantable medical device (“IMD”). The method includes configuring an IMD and an external device to communicate with one another through a protocol that utilizes a dedicated advertisement channel. The IMD periodically transmitting advertisement notices over the dedicated advertisement channel according to the protocol. The advertisement notices being transmitted periodically at an advertisement period over multiple cycles. The method further includes repeatedly scanning the advertisement channel, by the external device, for select scanning intervals in search of the advertisement notices, the scanning operation being repeated periodically at a scan period over the multiple cycles. The advertisement period and the scan period are independent of one another such that the advertisement and scan periods at least partially overlap intermittently after a number of cycles. When the external device detects one of the advertisement notices, the method includes establishing a communications link between the external device and the IMD.

BACKGROUND

Embodiments of the present invention generally relate to implantablemedical devices, and more particularly to establishing a communicationsession between implantable medical devices and external devices.

An implantable medical device (“IMD”) is a medical device that isconfigured to be implanted within a patient anatomy and commonly employone or more leads with electrodes that either receive or delivervoltage, current or other electromagnetic pulses (generally “energy”)from or to an organ or tissue for diagnostic or therapeutic purposes. Ingeneral, IMDs include a battery, electronic circuitry, such as a pulsegenerator and/or a microprocessor that is configured to handle RFcommunication with an external device as well as control patienttherapy. The components of the IMD are hermetically sealed within ametal housing (generally referred to as the “can”).

IMDs are programmed by and transmit data to external devices controlledby physicians and/or the patient. The external devices communicate byforming wireless bi-directional communication links with the IMDs.Recently, these external devices may include commercial wireless devicessuch as tablet computers, smartphones, and the like. For example, apatient may have an IMD that communicates with a tablet computer used bya physician to receive data from and change the settings of the IMD. Thetable computer receives data from the IMD regarding the patient'sphysiological state (e.g., the IMD may transmit stored data or sensedphysiological parameters). Based on the received data, the physician mayadjust the operating parameters of the IMD using the tablet computer.

To initiate the communication link, the IMD and the external deviceperform a handshaking protocol. During the handshaking protocol, the IMDmay have a predetermined timeframe to transmit an invitation data packetand to receive a connection request by the external device. Theinvitation packet may contain frequency synchronization information,address information, or the like. The external device may receive theinvitation data packet and transmit the connection request using theconnection specification protocol and data within the invitation datapacket (e.g., frequency synchronization information, addressinformation, and the like). If the IMD receives the connection requestwithin the predetermined timeframe the IMD may establish abi-directional communication link with the external device.

In order for the IMD to do both, transmit the invitation data packet andreceive the connection request within the predetermined timeframe, theIMD may have to continually perform the handshaking protocol (e.g.,transmit the invitation data packet) regardless of whether the externaldevice is present. By continually transmitting the invitation datapacket, the battery life of the IMD may decrease requiring replacementof the IMD. Consequently, there is a need of a method to change theperformance of the handshaking protocol by the IMD depending on whetherthe external device is present or not.

SUMMARY

In accordance with embodiments herein, a method is provided forestablishing a communication session with an implantable medical device(“IMD”). The method includes configuring an IMD and an external deviceto communicate with one another through a protocol that utilizes adedicated advertisement channel while periodically transmitting, fromthe IMD, advertisement notices over a dedicated advertisement channelaccording to the protocol. The advertisement notices being transmittedperiodically at an advertisement period. The method further includesrepeatedly scanning the advertisement channel, by the external device,for select scanning intervals in search of the advertisement notices,and the scanning operation being repeated periodically at a scan period.The advertisement period and the scan period are independent of oneanother such that the advertisement and scan period at least partiallyoverlap after a different number of cycles. And the method furtherincludes, when the external device detects one of the advertisementnotices, establishing a communications link between the external deviceand the IMD.

Optionally, the method may include lengthening the scan period in orderto shorten the advertisement period.

Optionally, the protocol may include multiple dedicated advertisementchannels and multiple data channels.

Optionally, the advertisement notices may be transmitted independentlyof the select scanning intervals, and the external device acknowledgesreceipt of the advertisement notice.

Optionally, when the IMD enters an advertising mode, the transmittingoperations of the IMD are performed in accordance with a BluetoothDiscovery Service defined within the protocol.

Optionally, the method may include triggering of an advertisement modewhen the IMD detects at least one of i) a magnetic field induced uponthe IMD, ii) a predetermined vibration scheme, iii) an inductivetelemetry signal, or iv) a select RFID signal.

In an embodiment, a communication system is provided. The communicationsystem includes an external device configured to communicate over awireless protocol that utilizes a dedicated advertisement channel. Theexternal device is configured to repeatedly scan the advertisementchannel during a select scan interval such that the scan interval isrepeated periodically at a scan period. The communication systemincludes an IMD configured to communicate over the wireless protocol.The IMD is configured to repeatedly transmit an advertisement noticeover the advertisement channel such that the advertisement notice isrepeated periodically at an advertisement period over multiple cycles.The advertisement period and the scan period of the communication systemare independent of one another, such that the advertisement and scanperiod at least partially overlap intermittently after a number ofcycle. The external device and the IMD are configured to establish acommunication link between the IMD and the external device when theexternal device detects one of the advertisement notices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a system block diagram of an exemplary system of anembodiment.

FIG. 2 illustrates a simplified block diagram of an IMD.

FIG. 3 illustrates a simplified block diagram of an external device.

FIG. 4 is a flowchart of a method for establishing a communicationsession between an IMD and an external device

FIG. 5 illustrates a timing signal diagram of an exemplary embodiment ofFIG. 1 using a time-multiplexing protocol.

FIG. 6 a illustrates a timing signal diagram of an exemplary embodimentof FIG. 1 using a specified frequency for an advertisement channel.

FIG. 6 b illustrates a timing signal diagram of an exemplary embodimentof FIG. 1 using a specified frequency for an advertisement channel.

DETAILED DESCRIPTION

The description that follows sets forth one or more illustrativeembodiments. It will be apparent that the teachings herein may beembodied in a wide variety of forms, some of which may appear to bequite different from those of the disclosed embodiments. Consequently,the specific structural and functional details disclosed herein aremerely representative and do not limit the scope of the disclosure. Forexample, based on the teachings herein one skilled in the art shouldappreciate that the various structural and functional details disclosedherein may be incorporated in an embodiment independently of any otherstructural or functional details. Thus, an apparatus may be implementedor a method practiced using any number of the structural or functionaldetails set forth in any disclosed embodiment(s). Also, an apparatus maybe implemented or a method practiced using other structural orfunctional details in addition to or other than the structural orfunctional details set forth in any disclosed embodiment(s).

FIG. 1 illustrates a simplified block diagram of an IMD 101 and anexternal device 201 (e.g., table computer, smart phone, laptop, or thelike) according to an embodiment of the present subject matter. The IMD101 may be implanted within a patient. The external device 201 isconfigured to establish a bi-directional communication link 104 with theIMD 101. The communication link 104 allows the external device 201 toreceive measurements from the IMD 101, and to program or sendinstructions to the IMD 101. The bi-directional communication link 104may use any standard wireless protocol such as Bluetooth Low Energy,Bluetooth, Wireless USB, Medical Implant Communication Service, WiFi,and the like. The external device 201 may be located within a home ofthe patient, a hospital, an automobile, at an office of the patient, orthe like. The IMD 101 may be one of various types of implantabledevices, such as, for example, an implantable pacemaker, implantablecardioverter-defibrillator (“ICD”), defibrillator, cardiac rhythmmanagement (“CRM”) device, neurostimulator, electrophysiology (“EP”)mapping and radio frequency (“RF”) ablation system, or the like.

FIG. 2 illustrates a block diagram of exemplary internal components ofthe IMD 101. The systems described herein can include or representhardware and associated instructions (e.g., software stored on atangible and non-transitory computer readable storage medium, such as acomputer hard drive, ROM, RAM, or the like) that perform the operationsdescribed herein. The hardware may include electronic circuits thatinclude and/or are connected to one or more logic-based devices, such asmicroprocessors, processors, controllers, or the like. These devices maybe off-the-shelf devices that perform the operations described hereinfrom the instructions described above. Additionally or alternatively,one or more of these devices may be hard-wired with logic circuits toperform these operations.

The IMD 101 is for illustration purposes only, and it is understood thatthe circuitry could be duplicated, eliminated or disabled in any desiredcombination to provide a device capable of treating the appropriatechamber(s) with cardioversion, defibrillation and/or pacing stimulationas well as providing for apnea detection and therapy. The housing 138for IMD 101, shown schematically in FIG. 2, is often referred to as the“can”, “case” or “case electrode” and may be programmably selected toact as the return electrode for all “unipolar” modes. The housing 138may further be used as a return electrode alone or in combination withone or more of the coil electrodes for shocking purposes. The housing138 further includes a connector (not shown) having a plurality ofterminals, 142, 152, 154, 156 and 158 (shown schematically and, forconvenience, the names of the electrodes to which they are connected areshown next to the terminals. A right atrial tip terminal (A_(R) TIP) 142is adapted for connection to the atrial tip electrode and a right atrialring terminal may be adapted for connection to right atrial ringelectrode. A left ventricular tip terminal (V_(L) TIP) 144, a leftatrial ring terminal (A_(L) RING) 146, and a left atrial shockingterminal (A_(L) COIL) 148 are adapted for connection to the leftventricular ring electrode, and a left atrial tip electrode and a leftatrial coil electrode respectively. A right ventricular tip terminal(V_(R) TIP) 152, a right ventricular ring terminal (V_(R) RING) 154, aright ventricular shocking terminal (R_(V) COIL) 156, and an SVCshocking terminal (SVC COIL) 158 are adapted for connection to the rightventricular tip electrode, right ventricular ring electrode, an RV coilelectrode, and an SVC coil electrode, respectively.

An acoustic terminal (AC T) 150 is adapted to be connected to anexternal acoustic sensor or an internal acoustic sensor, depending uponwhich (if any) acoustic sensors are used. Terminal 151 is adapted to beconnected to a blood sensor to collect measurements associated withglucose levels, natriuretic peptide levels, or catecholamine levels.

The IMD 101 includes a programmable microcontroller 160 which controlsoperation. The microcontroller 160 (also referred to herein as aprocessor module or unit) typically includes a microprocessor, orequivalent control circuitry, designed specifically for controlling thedelivery of stimulation therapy and may further include RAM or ROMmemory, logic and timing circuitry, state machine circuitry, and I/Ocircuitry. Typically, the microcontroller 160 includes the ability toprocess or monitor input signals (data) as controlled by program codestored in memory. The details of the design and operation of themicrocontroller 160 are not critical to the invention. Rather, anysuitable microcontroller 160 may be used that carries out the functionsdescribed herein. Among other things, the microcontroller 160 receives,processes, and manages storage of digitized cardiac data sets from thevarious sensors and electrodes. For example, the cardiac data sets mayinclude IEGM data, pressure data, heart sound data, and the like.

The IMD 101 includes an atrial pulse generator 170 and aventricular/impedance pulse generator 172 to generate pacing stimulationpulses for delivery by the right atrial lead 130, the right ventricularlead 131, and/or the coronary sinus lead 132 via an electrodeconfiguration switch 174. It is understood that in order to providestimulation therapy in each of the four chambers of the heart, theatrial and ventricular pulse generators, 170 and 172, may includededicated, independent pulse generators, multiplexed pulse generators orshared pulse generators. The pulse generators, 170 and 172, arecontrolled by the microcontroller 160 via appropriate control signals,176 and 178, respectively, to trigger or inhibit the stimulation pulses.

The IMD 101 includes a neuro stimulation pulse generator circuit 192 togenerate stimulation pulses for a brain or spinal cord nervous system.The stimulation pulses are delivered by a plurality of electrodesthrough the neuro output lead 191. The neuro stimulation pulse generatorcircuit 192 is controlled by the microcontroller 160 via appropriatecontrol signals 193 to trigger or generate the stimulation pulses.

The microcontroller 160 further includes timing control circuitry 179used to control the timing of such stimulation pulses (e.g., pacingrate, atria-ventricular (AV) delay, atrial interconduction (A-A) delay,or ventricular interconduction (V-V) delay, etc.) as well as to keeptrack of the timing of refractory periods, blanking intervals, noisedetection windows, evoked response windows, alert intervals, markerchannel timing, and the like. Switch 174 includes a plurality ofswitches for connecting the desired electrodes to the appropriate I/Ocircuits, thereby providing complete electrode programmability.Accordingly, the switch 174, in response to a control signal 180 fromthe microcontroller 160, determines the polarity of the stimulationpulses (e.g., unipolar, bipolar, etc.) by selectively closing theappropriate combination of switches (not shown) as is known in the art.

Atrial sensing circuit 182 and ventricular sensing circuit 184 may alsobe selectively coupled to the right atrial lead 130, coronary sinus lead132, and the right ventricular lead 131, through the switch 174 fordetecting the presence of cardiac activity in each of the four chambersof the heart. Accordingly, the atrial (ATR SENSE) and ventricular (VTRSENSE) sensing circuits, 182 and 184, may include dedicated senseamplifiers, multiplexed amplifiers or shared amplifiers. The outputs ofthe atrial and ventricular sensing circuits, 182 and 184, are connectedto the microcontroller 160 which, in turn, are able to trigger orinhibit the atrial and ventricular pulse generators, 170 and 172,respectively, in a demand fashion in response to the absence or presenceof cardiac activity in the appropriate chambers of the heart.

Cardiac signals are also applied to the inputs of an analog-to-digital(A/D) data acquisition system 190. The data acquisition system 190 isconfigured to acquire IEGM signals, convert the raw analog data into adigital IEGM signal, and store the digital IEGM signals in memory 194for later processing and/or RF transmission to the external device 201.The data acquisition system 190 is coupled to the right atrial lead 130,the coronary sinus lead 132, and the right ventricular lead 131 throughthe switch 174 to sample cardiac signals across any combination ofdesired electrodes. The data acquisition system 190 may also be coupled,through switch 174, to one or more of the acoustic sensors. The dataacquisition system 190 acquires, performs A/D conversion, produces andsaves the digital pressure data, and/or acoustic data.

The controller 160 controls the acoustic sensor and/or a physiologicsensor to collect heart sounds during one or more cardiac cycles. Theheart sounds include sounds representative of a degree of blood flowturbulence. The acoustic sensor and/or physiologic sensor collects theheart sounds that include S1, S2 and linking segments. The S1 segment isassociated with initial systole activity. The S2 segment is associatedwith initial diastole activity. The linking segment is associated withat least a portion of heart activity occurring between the S1 and S2segments during a systolic interval between the initial systole anddiastole activity. The controller 160 changes a value for at least oneof the pacing parameters between the cardiac cycles. The controller 160implements one or more processes described herein to determine valuesfor one or more pacing parameters that yield a desired level ofhemodynamic performance.

The controller 160 includes an analysis module 171 and a setting module173 that function in accordance with embodiments described herein. Theanalysis module 171 analyzes a characteristic of interest from the heartsounds within at least a portion of the linking segment. Thecharacteristic of interest is indicative of an “amount” of the heartsounds over at least a portion of the systolic interval between theinitial systole and diastole activity. The amount of the heart soundsmay be derived in different manners, such as determining the energycontent, intensity and the like, as well as relations there between. Thelevel of the characteristic changes as the pacing parameter is changed.The setting module 173 sets a desired value for the pacing parameterbased on the characteristic of interest from the heart sounds for atleast the portion of the linking segment. The pacing parameter mayrepresent at least one of an AV delay, a VV delay, a VA delay,intra-ventricular delays, electrode configurations and the like. Thecontroller 160 changes at least one of the AV delay, the VV delay, theVA delay, the intra-ventricular delays, electrode configurations andlike in order to reduce systolic turbulence and regurgitation.

The microcontroller 160 is coupled to memory 194 by a suitabledata/address bus 196, wherein the programmable operating parameters usedby the microcontroller 160 are stored and modified, as required, inorder to customize the operation of IMD 101 to suit the needs of aparticular patient. The memory 194 also stores data sets (raw data,summary data, histograms, etc.), such as the IEGM data, heart sounddata, pressure data, Sv02 data and the like for a desired period of time(e.g., 1 hour, 24 hours, 1 month). The memory 194 may store instructionsto direct the microcontroller 160 to analyze the cardiac signals andheart sounds identify characteristics of interest and derive values forpredetermined statistical parameters. The IEGM, pressure, and heartsound data stored in memory 194 may be selectively stored at certaintime intervals, such as 5 minutes to 1 hour periodically or surroundinga particular type of arrhythmia of other irregularity in the heartcycle. For example, the memory 194 may store data for multiplenon-consecutive 10 minute intervals.

The pacing and other operating parameters of the IMD 101 may benon-invasively programmed into the memory 194 through an RF circuit 110in bi-directional wireless communication with the external device 201.The RF circuit 110 is controlled by the microcontroller 160 and receivesdata for transmission by a control signal 111. The RF circuit 110 allowsintra-cardiac electrograms, pressure data, acoustic data, Sv02 data, andstatus information relating to the operation of IMD 101 (as contained inthe microcontroller 160 or memory 194) to be sent to the external device201 through an established bi-directional communication link 104. The RFcircuit 110 also allows the external device 201 to program new pacingparameters for the setting module 173 used by the IMD 101.

To establish the communication link 104 between the external device 201and the IMD 101, the microcontroller 160 instructs the RF circuit 110 totransmit an advertisement notice on an advertisement channel. Theadvertisement channel is a point to multipoint, unidirectional, channelto carry a repeating pattern of system information messages such asnetwork identification, allowable RF channels to establish thecommunication link 104, and the like that is included within theadvertisement notice. The advertisement notice may be repeatedlytransmitted after a set duration or an advertisement period until thecommunication link 104 is established with the external device 201.

The length of the advertisement period may be adjusted by themicrocontroller 160 when entering an advertisement mode. During theadvertisement mode, the microcontroller 160 may reduce the length of theadvertisement period relative to not being in the advertisement mode.The reduced length of the advertisement period results in the RF circuit110 transmitting more or an increased number of advertisement noticesrelative to not being in the advertisement mode. The microcontroller 160may enter the advertisement mode after detecting a predetermined signaldirected at the IMD 101.

The microcontroller 160 supports a particular wireless communicationprotocol while communicating with the external device 201, such asBluetooth low energy, Bluetooth, WiFi, Medical Implant CommunicationService (“MICS”), WiFi, or the like. Protocol firmware is stored inmemory 194, and is accessed by the microcontroller 160 via the data bus196. The protocol firmware provides the wireless protocol syntax for themicrocontroller 160 to assemble data packets, establish communicationlinks, and partition data received from the external device 201.

The IMD 101 may also include an accelerometer or other physiologicsensor 112, commonly referred to as a “rate-responsive” sensor becauseit is typically used to record the activity level of the patient oradjust pacing stimulation rate according to the exercise state of thepatient. Optionally, the physiological sensor 112 may further be used todetect changes in cardiac output, changes in the physiological conditionof the heart, or changes in activity (e.g., detecting sleep and wakestates) and movement positions of the patient. While shown as beingincluded within IMD 101, it is to be understood that the physiologicsensor 112 may also be external to the IMD 101, yet still be implantedwithin or carried by the patient. A common type of rate responsivesensor is an activity sensor incorporating an accelerometer or apiezoelectric crystal, which is mounted within the housing 138 of theIMD 101.

The physiologic sensor 112 may be used as the acoustic sensor that isconfigured to detect the heart sounds. For example, the physiologicsensor 112 may be an accelerometer that is operated to detect acousticwaves produced by blood turbulence and vibration of the cardiacstructures within the heart (e.g., valve movement, contraction andrelaxation of chamber walls and the like). When the physiologic sensor112 operates as the acoustic sensor, it may supplement or replaceentirely acoustic sensors. Other types of physiologic sensors are alsoknown, for example, sensors that sense the oxygen content of blood,respiration rate and/or minute ventilation, pH of blood, ventriculargradient, etc. However, any sensor may be used which is capable ofsensing a physiological parameter that corresponds to the exercise stateof the patient and, in particular, is capable of detecting arousal fromsleep or other movement.

The IMD 101 additionally includes a battery 113, which providesoperating power to all of the circuits shown. The IMD 101 is shown ashaving impedance measuring circuit 115 which is enabled by themicrocontroller 160 via a control signal 114. Herein, impedance isprimarily detected for use in evaluating ventricular end diastolicvolume (EDV) but is also used to track respiration cycles. Other usesfor an impedance measuring circuit include, but are not limited to, leadimpedance surveillance during the acute and chronic phases for properlead positioning or dislodgement; detecting operable electrodes andautomatically switching to an operable pair if dislodgement occurs;measuring respiration or minute ventilation; measuring thoracicimpedance for determining shock thresholds; detecting when the devicehas been implanted; measuring stroke volume; and detecting the openingof heart valves, etc. The impedance measuring circuit 115 isadvantageously coupled to the switch 174 so that impedance at anydesired electrode may be obtained.

FIG. 3 illustrates a functional block diagram of the external device 201that is operated in accordance with the processes described herein andto interface with the IMD 101 as described herein. The external device201 may be a workstation, a portable computer, a tablet computer, an IMDprogrammer, a PDA, a cell phone and the like. The external device 201includes an internal bus that may connect/interface with a CentralProcessing Unit (“CPU”) 202, ROM 204, RAM 206, a hard drive 208, thespeaker 210, a printer 212, a CD-ROM drive 214, a floppy drive 216, aparallel I/O circuit 218, a serial I/O circuit 220, the display 222, atouchscreen 224, a standard keyboard 226, custom keys 228, and an RFsubsystem 230. The internal bus is an address/data bus that transfersinformation between the various components described herein. The harddrive 208 may store operational programs as well as data, such aswaveform templates and detection thresholds.

The CPU 202 typically includes a microprocessor, a micro-controller, orequivalent control circuitry, designed specifically to controlinterfacing with the external device 201 and with the IMD 101. The CPU202 may include RAM or ROM memory, logic and timing circuitry, statemachine circuitry, and I/O circuitry to interface with the IMD 101. Thedisplay 222 (e.g., may be connected to the video display 232). Thetouchscreen 224 may display graphic information relating to the IMD 101.The display 222 displays various information related to the processesdescribed herein. The touchscreen 224 accepts a user's touch input 234when selections are made. The keyboard 226 (e.g., a typewriter keyboard236) allows the user to enter data to the displayed fields, as well asinterface with the RF subsystem 230. Furthermore, custom keys 228 turnon/off 238 (e.g., EVVI) the external device 201. The printer 212 printscopies of reports 240 for a physician to review or to be placed in apatient file, and a speaker 210 provides an audible warning (e.g.,sounds and tones 242) to the user. The parallel I/O circuit 218interfaces with a parallel port 244. The serial I/O circuit 220interfaces with a serial port 246. The floppy drive 216 acceptsdiskettes 248. Optionally, the floppy drive 216 may include a USB portor other interface capable of communicating with a USB device such as amemory stick. The CD-ROM drive 214 accepts CD ROMs 250.

The RF subsystem 230 includes a central processing unit (CPU) 252 inelectrical communication with an RF circuit 254, which communicates withboth an IEGM circuit 256 and an analog out circuit 258. The RF subsystemmay be connected to a telemetry wand 262. The circuit 256 may beconnected to leads 260. The analog out circuit 258 includescommunication circuits to communicate with analog outputs 264. Theexternal device 201 may wirelessly communicate with the IMD 101 andutilize protocols, such as Bluetooth, Bluetooth low energy, WiFi, MICS,and the like. Alternatively, a hard-wired connection may be used toconnect the external device 201 to the IMD 101.

FIG. 4 illustrates a flowchart of a method 300 for establishing acommunication session with an IMD (e.g., 101). The method 300 may beimplemented as a software algorithm, package, or system that directs oneor more hardware circuits or circuitry to perform the actions describedherein. For example, the operations of the method 300 may representactions to be performed by one or more circuits that include or areconnected with processors, microprocessors, controllers,microcontrollers, Application Specific Integrated Circuits (ASICs),Field-Programmable Gate Arrays (FPGAs), or other logic-based devicesthat operate using instructions stored on a tangible and non-transitorycomputer readable medium (e.g., a computer hard drive, ROM, RAM, EEPROM,flash drive, or the like), such as software, and/or that operate basedon instructions that are hardwired into the logic of the

.

At least one technical effect of at least one portion of the methodsdescribed herein includes establishing a communication session with anIMD (e.g., 101) and an external device (e.g., 201) by i) configuring theIMD and the external device to communicate with one another through aprotocol that utilizes at least one dedicated advertisement channel, ii)periodically transmit, from the IMD, advertisement notices or packetsover the dedicated advertisement channel according to the protocol,wherein the advertisement notices are transmitted periodically at anadvertisement period, iii) repeatedly scanning the advertisementchannel, by the external device, for select scanning intervals in searchof the advertisement notices, the scanning operation being repeatedperiodically at a scan period, wherein the advertisement period and scanperiod are independent of one another such that the advertisement andscan periods at least partially overlap intermittently after differentnumber of cycles, and iv) when the external device detects one of theadvertisement notices, establishing a communications link between theexternal device and the IMD.

At 301, the method configures an IMD 101 and an external device 201 tocommunicate with one another through a protocol. For example, the RFcircuit 110 of the IMD 101 and the RF circuit 254 of the external device201 may be configured to communicate utilizing Bluetooth Low Energy (orBluetooth Smart), Bluetooth, MICS, WiFi, or the like. Various protocolsmay be used, provided that the protocol utilizes a dedicatedadvertisement channel.

The advertisement channel is a point to multipoint, unidirectional,channel. The advertisement channel carries a repeating pattern of systeminformation messages. The system information messages may describe theidentity, configuration, and/or available features of the IMD 101. Theadvertisement channel is used by devices (external device 201, IMD 101)to discover new/other devices, to initiate communication links withother devices, and/or to broadcast connection/address information. Theadvertisement channel may represent a predetermined bandwidth within anoperating frequency range of the protocol. Additionally oralternatively, the advertisement channel may represent a predeterminedtime slot (e.g., 406 in FIG. 5) with fixed length within a time period(e.g., 405) comprising a plurality of different time slots.

In one embodiment, optionally, the external device 201 and multiple IMDs101 utilize the Bluetooth Low Energy (“BLE”) protocol. The BLE protocoloperates within a frequency range of 2400-2483.5 MHz (including guardbands). The operational frequency range is divided into 40 RF channelshaving a 2 MHz bandwidth. Three RF channels are dedicated advertisementchannels having center frequencies at 2402 MHz, 2426 MHz, and 2480 MHz.The remaining RF channels are dedicated data channels. Data channels areutilized by devices having an established BLE communication link toexchange data. For example, the external device 201 has an establishedcommunication link with the IMD 101 such that data is exchanged betweenthe external device 201 and the IMD 101 over the data channel. AnotherIMD, without an established communication link, broadcastsconnection/address information along the advertisement channel, forinstance at 2404 MHz.

At 302, the IMD 101 transmits one or more advertisement notices, over adedicated advertisement channel, periodically during an advertisementperiod. The advertisement notice may be a data packet or a pulseconfigured to elicit a response from another device to establish acommunication link. The advertisement notice may contain frequencysynchronization information utilized to form the communication link 104,address information of the IMD 101, address information of the externaldevice 201, and the like. The advertisement notice may be repeated, at aset or variable interval or advertisement period, until thecommunication link 104 is established. The advertisement periodrepresents the length of time the IMD 101 may transmit anotheradvertisement notice after a previous transmission by the IMD 101 of theadvertisement notice. Optionally, the advertisement period may be inputby a user (e.g., physician using an external device).

For example, FIG. 5 illustrates a timing signal diagram 400 of anexemplary embodiment having the external device 201 and the IMD 101using a time-division multiplexing wireless protocol. Under theprotocol, the external device 201 and the IMD 101 transmit/receive dataalong the same frequency band over a repeating time frame 405. The timeframe 405 is divided into fixed channels 403, 404, 406, and 410 of afixed length. The channels may be assigned to a device, or specificfunctions such as a synchronization channel 403 and an advertisementchannel 406. The synchronization channel 403 is used by the externaldevice 201 to transmit a synchronization signal that is used tosynchronize other devices within the network to the time frame 405 andchannel lengths. The synchronization channel 403 may be predeterminedand/or configured by the user (e.g., physician) of the external device201, such that the length of the timing frame 405 and/or the fixedchannels (404, 406, 410) may be extended or shortened.

In one embodiment, optionally, the time frame 405 may have a defaultlength of, for example, 20 ms, and divided into 5 milliseconds (ms)fixed channels (403, 404, 406, 410). The user of the external device 201may shorten (or lengthen) the time frame 405 to a length of, forexample, 12 ms with fixed channel length of 3 ms, and reconfigure thesynchronization channel 403 to include the new time frame 405 and fixedchannel lengths. The IMD 101 analyzes the synchronization channel 403containing the current timing specifications with the reconfiguredadvertisement channel 406, and updates the timing specification on theprotocol syntax stored in the memory 194. The IMD 101 transmits anadvertisement notice 411 along the reconfigured advertisement channel406 to form a communication link 104 with the external device 201. TheIMD 101 may continually retransmit the advertisement notice 411 over theadvertisement channel 406 until the communication link 104 isestablished. The retransmission of the advertisement notice 411 occursat the beginning of every advertisement period 408 or, using the aboveexample, every 12 ms, such that, the advertisement notice 411 isrepeatedly transmitted during the advertisement channel 406.

Once the external device 201 receives the advertisement notice 411, theexternal device 201 may transmit the data channel specifications for theIMD 101 on the data channel 404 to establish the communication link 104between the external device 201 and the IMD 101.

At 303, the external device 201 scans the advertisement channel duringselect intervals in search of one or more advertisement notices. Theexternal device repeats the scan periodically at a scan period. Theexternal device 201 monitors or scans the advertisement channel foradvertisement notices using the RF circuit 254.

For example, FIG. 6 a illustrates a timing diagram 600 of an exemplaryembodiment having the external device 201 and the IMD 101 using awireless protocol that utilizes a specified frequency for anadvertisement channel. The IMD 101 is transmitting an advertisementnotice 605 on the advertisement channel using the RF circuit 110. Theadvertisement period 602, for example, may be 5 seconds (s) such thatthe advertisement notice 605 may be repeated every 5 s. Optionally, theadvertisement period 602 may be longer or shorter than the aboveexample. Additionally or alternatively, the advertisement period may bepredetermined and stored in memory 194 of the IMD 101.

The user, using the touchscreen 224 or standard keyboard 236, mayinstruct the external device 201 to establish the communication link 104with the IMD 101. The CPU 202 instructs the RF subsystem 230 to outputthe received transmissions from the advertisement channel (e.g., 2402MHz, 2426 MHz, 2480 MHz), for example, every 1 s. The output of the RFsubsystem 230 corresponds to a scanning interval 603. The RF subsystemrepeats the scanning interval 603 every scan period 601 such that thescanning interval 603 may be repeated, for example, every 4 s. Thescanning interval 603 and/or scan period 601 may be longer or shorterthan the above example. Additionally or alternatively, the scanninginterval 603 and/or scan period 601 may be a predetermined length storedon the ROM 204, the RAM 206, or the hard drive 208. Optionally, thescanning interval 603 and/or scan period 601 is configured by the user,such that, the interval 603 or period 601 may be increased or decreased.The RF subsystem 230 continually repeats the scanning interval 603 untilthe CPU 202 acknowledges receipt of the advertisement notice 605.

The scan period 601 and the advertisement period 602 occur independentand asynchronous with respect to one another, such that theadvertisement notices 605 intermittently overlap the scan intervals at604 and 606. Each period length is predetermined from distinct andseparate sources. The scan period 601 is predetermined or configured bythe user of the external device 201. Separately, the advertisementperiod 602 is predetermined by the protocol syntax stored in the memory194 of the IMD 101. One of the scan period 601 and the advertisementperiod 602 may be altered, while, the length of the other period (e.g.,advertisement period 602, scan period 601) remains constant.

The scan period 601 has an asynchronous phased relation with respect tothe advertisement period 602 in order that a phase interval 615 betweenbeginnings of the scanning intervals 603 and advertisement notices 605continuously (or intermittently) changes.

For example, the scan period 601 may be 4 s having the scanning interval603 of 1 s, and advertisement period 602 may be 5 s having theadvertisement notice 605 of 1.5 s. The different lengths of the periods601 and 602 represent the asynchronous phased relationship with respectto each other. The asynchronous phased relationship causes theadvertisement notice 605 and the scanning interval 603 to begin atdifferent times thus creating phase intervals 615. The length of thephase interval 615 can be extended or shortened by changing theadvertisement period 602 of the IMD 101 or the scan period 601 of theexternal device 201. Thus, by configuring the advertisement period 602or the scan period 601, the phase interval 615 may continuously changeor be changed intermittently after a set number of cycles. The beginningof the cycle occurs at the transmission of the advertisement notice 605or the scan interval 603. The phase interval 615 may be controlled bythe user changing the scan period 603 of the external device 201 or bythe microcontroller 160 changing the advertisement period 602 of the IMD101.

For example, the phase interval 615 of the timing diagram 600, iscontinuously changing after each cycle. The phase interval 615 a,measured between the beginning of the advertisement notice 605 a and thebeginning of the scan interval 603 a, may be approximately 1.5 s long.The advertisement notice 605 a and the scanning interval 603 a do notpartially overlap. The phase interval 615 b, between the advertisementnotice 605 b and the scanning interval 603 b, may be approximately 750ms long. The phase interval 615 c, between the advertisement notice 605c and the scanning interval 603 c, may be approximately 250 ms long.Accordingly, the length of the phase interval 615 continuously changeseach cycle. The changes in the length of the phase interval 615illustrate that each cycle or repetition of the scanning interval 603and the advertisement notice 605 shifts with respect to each otherallowing for partially overlapping events at 604 and 606 to occur. Forinstance, only the phase intervals 615 b-615 c are associated withpartially overlapping advertisement notices 605 b-c and scanningintervals 615 b-c. Although the periods 601, 602 are asynchronous, thescanning intervals 602 and the advertisement notices 605 will partiallyoverlap and enable the external device 201 intermittently or after a setnumber of cycles to receive the advertisement notice 605. The overlapsoccur intermittently, in that after a number of cycles the interval 603and notice 602 will partially overlap in fewer cycles than the number ofcycles. For example, the interval 603 and notice 602 partially overlapafter the fourth and fifth cycle of the scanning interval 603 or thethird and fourth cycle of the advertisement notice 605.

Optionally, the IMD 101 may have an advertisement mode that decreasesthe number of cycles needed until the communication link 104 isestablished, by increasing the likelihood of the scanning interval 603partially overlapping the advertisement notice 605. During anadvertisement mode, the microcontroller 160 may decrease the length ofthe advertisement period 602, relative to not being in the advertisementmode, thus, increasing the number of advertisement notices 605 in a timeframe 609. The increased number of advertisement notices 605 increasethe number of partial overlaps with the scanning intervals 603, allowingthe external device 201 to detect or receive the advertisement notice605 in a shorter amount of cycles relative to the IMD 101 not being inan advertisement mode.

For example, FIG. 6 b illustrates a timing diagram 650 of an exemplaryembodiment having the external device 201 and IMD 101 using a wirelessprotocol that utilizes a specified frequency for the advertisementchannel. The external device 201 is repeatedly scanning theadvertisement channel, such that, the scan period 601 of the scanninginterval 603, for example, may be 4 s. Optionally, the scan interval 603may be longer or shorter than that illustrated in FIG. 6 b. The IMD 101operates in two modes, a default mode 610 and the advertisement mode611. The advertisement notices 605 and 613 for each mode 610 and 611 isillustrated in timing diagram 650.

When the IMD 101 is in the default mode 610, the IMD 101 transmits theadvertisement notice 605 repeatedly such that the advertisement period602, for example, may be 5 s. The advertisement notices 605 and thescanning intervals 603 partially overlap after approximately 12 s and 17s, or at the fourth and fifth cycles of the scanning interval 603.

When the IMD 101 is in the advertisement mode 611, the advertisementperiod may be reduced, for example, to 2.5 s. The reduced advertisementperiod 612 increases the number of advertisement notices 613 transmittedby the IMD 101 than in the default mode 611 during the same period. Suchthat after, for example, 20 s (the time period 609), the IMD 101 in theadvertisement mode will have had eight cycles or transmitted eightadvertisement notices 613 while only four advertisement notices 605would have been transmitted in the default mode 610. While in theadvertisement mode 611, the advertisement notices 613 and the scanningintervals 603 partially overlap, for example, after approximately 4 s,12 s, 17 s, or at the second, fourth, and fifth cycle of the scanninginterval 603. Thus, the IMD 101 operating in the advertisement mode 611allows the external device 201 to receive the advertisement notice 605in a shorter amount time and with more partial overlaps relative to theIMD 101 not being in an advertisement mode 611.

At 304, the method determines whether the external device 201 detectsthe advertisement notice. For example, the external device 201 receivesthe advertisement notice in the form of a data packet transmitted from aremote device. The CPU 202 analyzes or compares the data packet with theprotocol syntax stored on the ROM 204, the RAM 206, or the hard drive208. The protocol syntax may include the structure of an advertisementnotice (e.g., data packet specifications, appropriate number of bits,frequency, or the like) utilized by the wireless protocol. Optionally,the advertisement notice may include a unique code designating thepacket as an advertisement. By comparing the protocol syntax with thedata packet, the CPU 202 determines whether the received data packet isan advertisement notice using the wireless protocol of the externaldevice 201. If the received data packet is determined not to be anadvertisement notice, the external device 201 may continue scanning theadvertisement channel.

In one embodiment, optionally, the external device may acknowledgereceipt of the advertisement notice. For example, when the CPU 202determines that the data packet received by the RF circuit 254 is theadvertisement notice 605, the CPU 202 may output an acknowledgmentreceipt (e.g., data packet) to be transmitted by the RF circuit 254along the advertisement channel. The acknowledgment receipt may includeaddress information of the external device 201 and/or the IMD 101, or arequest for further information or data from the IMD 101 to establishthe communication link 104 (e.g., transceiver identification, patientidentification, frequency information, or the like).

At 305 the method establishes a communication link between the IMD 101and the external device 201. The communication link 104 is establishedonce data is exchanged between the IMD 101 and the external device 201.

For example, the advertisement notice 605 may contain specifications forthe frequency and/or timing specifications for the data channel toexchange data with the IMD 101. Once the CPU 202 of the external device201 determines the advertisement notice has been received, the CPU 202will partition the data channel and the address of the IMD 101 from theadvertisement notice. The CPU 202 constructs a data packet by addingpacket frames to conform to the protocol such as the address of the IMD101 and/or external device 201, error detection codes such as CRC, apayload, or the like. The payload may include instructions and/ormeasurement requests from the user intended for the IMD 101. Once thedata packet has been formed, the CPU 202 outputs the data packet to theRF subsystem 230 to be transmitted along the data channel to the IMD101.

The RF circuit 110 receives the data packet and outputs to themicrocontroller 160. The microcontroller 160 may store the data packetin memory 194 for analysis. The microcontroller 160 determines whetherthe data packet is in response to the advertisement notice 605 bycomparing the address information of the data packet with the addresstransmitted by the IMD 101 within the advertisement notice 605. If theaddress information matches, the microcontroller 160 partitions thepayload from the data packet and carries out the instructions of thepayload by comparing the instructions to the stored instruction set onthe memory 194. Optionally, the microcontroller 160 may compare theaddress information of the external device 201 on the data packet with apermissible links table stored in memory 194 to determine whether theIMD 101 should ignore or partition the payload of the data packet. Oncethe microcontroller 160 completes the requested instructions, themicrocontroller 160 constructs a responsive data packet to the externaldevice 201 conforming to the protocol. Once the responsive data packetis constructed, the microcontroller 160 outputs the responsive datapacket to the RF circuit 110 establishing the communication link 104with the external device 201.

In one embodiment, optionally, when the IMD 101 enters into theadvertisement mode, the transmitting operations of the protocol utilizedby the IMD 101 are in accordance with the Bluetooth Discovery Serviceused by the Bluetooth and/or BLE protocol. The Bluetooth and BLEprotocols are defined within “Bluetooth Specification Version 4.0 [Vol0], published Jun. 30, 2011 (incorporated herein by reference).

For example, the microcontroller 160 triggers the IMD 101 into theadvertisement mode by constructing the advertisement notice inaccordance with the Bluetooth Discovery Service used by the BLEprotocol. The advertisement notice contains a preamble, an accessaddress, a protocol data unit (“PDU”), and a CRC. The preamble andaccess address are predetermined eight and 32 bit values that may bestored on the memory 194. The PDU contains a 16 bit header and avariable sized payload. The payload contains the address field for theIMD 101.

Once the advertisement notice is constructed, the microcontroller 160may output the advertisement notice to the RF circuit 110 fortransmission on the advertisement channel having a center frequency at2402 MHz, 2426 MHz, or 2480 MHz. The advertisement period may be lessthan or equal to 10 ms or may be a predetermined length stored on thememory 194.

The microcontroller 160 will instruct the RF circuit 110 to monitor forrequests by the external device 201 on the advertisement channel of thetransmitted advertisement notice. If no request is received by the RFcircuit 110 by the end of the advertisement period, the microcontroller160 may instruct the RF circuit 110 to transmit another advertisementnotice on the same or another advertisement channel. Alternatively, ifthe RF circuit 110 receives a connection request from the externaldevice 201 containing the address of the IMD 101, the microcontroller160 may establish a communication link 104 with the external device 201.

In one embodiment, optionally, the IMD 101 enters into the advertisementmode when the IMD 101 detects an induced magnetic field upon the IMD101. A magnetic sensor such as a hall sensor, MEMS sensor, or the likemay be operatively coupled to the A/D data acquisition system 190 of theIMD 101. The A/D data acquisition system 190 measures and stores theoutput of the magnetic sensor. The A/D data acquisition system 190compares the stored measurements for sudden changes in the magneticfield of the IMD 101, such that, the A/D data acquisition system 190detects whether a magnetic field is induced upon the IMD 101. Once themagnetic field is detected, the A/D data acquisition system 190 outputsa detection signal to the microcontroller 160. The microcontroller 160responds by triggering the IMD 101 into the advertisement mode.

The magnetic field may be induced by the user (e.g., patient, physician)of the external device 201 intending to establish the communication link104 between the external device 201 and the IMD 101. Optionally, asolenoid may be coupled to the external device 201, allowing the user toinduce the magnetic field upon the IMD 101 from the external device 201.

In one embodiment, optionally, the IMD 101 may enter into theadvertisement mode when the IMD 101 detects a predetermine vibrationscheme. The vibration scheme may be a signal output to a vibration motorcoupled to the external device 201 that corresponds to a speed and/orpattern. The vibration motor may be a DC motor with an offset mass orweight attached to the shaft. Once the signal output is received by thevibration motor, the vibration motor spins the shaft at a speed and/ordirection that corresponds to the signal output. The offset mass on theshaft causes the motor to be displaced or vibrate. The signal output maybe activated by the user of the external device 201 intending toestablish the communication link 104 by using the touchscreen 224, thestandard keyboard 226, or custom keys 228. The CPU 202 retrieves thevibration scheme from the ROM 204, the RAM 206, the hard drive 208corresponding to the connection instruction from the user. The CPU 202,through the Serial I/O Circuit 220, outputs the signal output to thevibration motor. The vibration motor is placed on or near the IMD 101such that the vibration motor causes the IMD 101 to be displaced by thevibrations of the vibration motor.

The physiologic sensor 112, configured as the accelerometer, of the IMD101 detects the displacement or changes in position of the IMD 101 fromthe vibrations. The physiologic sensor 112 outputs position measurementsof the IMD 101 to the microcontroller 160. The microcontroller 160 maycompare the changes in the position measurements to determine a speed orpattern which will correspond to the vibration scheme from the vibrationmotor. The microcontroller 160 compares the measured vibration scheme toa predetermined vibration scheme stored on the memory 194. Once themicrocontroller 160 determines that the two vibration schemes areapproximately similar within a set threshold or error rate, themicrocontroller 160 triggers the IMD 101 into the advertisement mode.The set threshold may be a predetermined amount stored on the memory194.

In one embodiment, optionally, the IMD 101 may enter into theadvertisement mode when the IMD 101 detects an inductive telemetrysignal. For example, the telemetry wand 262 of the external device 201may include an inductor coil circuitry. The RF circuit 110 of the IMD101 may be configured with an inductive telemetry antenna. Once the userinstructs the external device 201 to form the connection link 104 withthe IMD 101, the CPU 202 outputs a corresponding telemetry signal storedon the ROM 204, the RAM 206, or the hard drive 208 to the RF subsystem230. The telemetry signal, transmitted by the telemetry wand 262,changes the inductive coupling between the telemetry wand 262 and theinductive telemetry antenna of the RF circuit 110. The microcontroller160 measures an electrical change caused by the inductive coupling, suchas a voltage or a current change from the output of the RF circuit 110,to determine the telemetry signal. The microcontroller 160 compares themeasured telemetry signal with a predetermined telemetry signal storedin memory 194. Once the microcontroller 160 determines that thetelemetry signals are approximately similar within a set threshold, themicrocontroller 160 triggers the IMD 101 into the advertisement mode.

In one embodiment, optionally, the IMD 101 may enter into theadvertisement mode when the IMD 101 detects a select RFID signal. Forexample, the RF subsystem 230 includes an RFID circuit. The RFID circuittransmits a predetermined identification signal that corresponds to theexternal device 201. The identification signal may be stored on the ROM204, the RAM 206, the hard drive 208, or an internal memory of the RFIDcircuit. Alternatively or additionally, the identification signal may beinput by the user using the touchscreen 224, standard keyboard 226, orcustom keys 228.

The user instructs the external device 201 to form a connection link 104with the IMD 101. The CPU 202 initiates the communication linkinstructions, by outputting the identification signal to be transmittedby the RFID circuit. Once the identification signal is received by theIMD 101, the RF circuit 110 outputs the identification signal to themicrocontroller 160. The microcontroller 160 determines whether to enterinto an advertisement mode by comparing the identification signal withstored identification signals on memory 194. The stored identificationsignals may be a table or list of all external devices that may form acommunication link 104 with the IMD 101. Once the microcontroller 160finds a match for the identification signal, the microcontroller 160triggers the IMD 101 into the advertisement mode.

The memory 194 may include or represent one or more memories (e.g., atangible and non-transitory computer readable memory, such as a computerhard drive, EEPROM, ROM, RAM, or the like) having a table, list,database, or other memory structure used to store information used inconjunction with performing one or more of the methods described herein.

One or more of the operations described above in connection with themethods may be performed using one or more processors. The differentdevices in the systems described herein may represent one or moreprocessors, and two or more of these devices may include at least one ofthe same processors. In one embodiment, the operations described hereinmay represent actions performed when one or more processors (e.g., ofthe devices described herein) are hardwired to perform the methods orportions of the methods described herein, and/or when the processors(e.g., of the devices described herein) operate according to one or moresoftware programs that are written by one or more persons of ordinaryskill in the art to perform the operations described in connection withthe methods.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the inventivesubject matter without departing from its scope. While the dimensionsand types of materials described herein are intended to define theparameters of the inventive subject matter, they are by no meanslimiting and are exemplary embodiments. Many other embodiments will beapparent to one of ordinary skill in the art upon reviewing the abovedescription. The scope of the inventive subject matter should,therefore, be determined with reference to the appended claims, alongwith the full scope of equivalents to which such claims are entitled. Inthe appended claims, the terms “including” and “in which” are used asthe plain-English equivalents of the respective terms “comprising” and“wherein.” Moreover, in the following claims, the terms “first,”“second,” and “third,” etc. are used merely as labels, and are notintended to impose numerical requirements on their objects. Further, thelimitations of the following claims are not written inmeans-plus-function format and are not intended to be interpreted basedon 35 U.S.C. §112, sixth paragraph, unless and until such claimlimitations expressly use the phrase “means for” followed by a statementof function void of further structure.

This written description uses examples to disclose several embodimentsof the inventive subject matter and also to enable a person of ordinaryskill in the art to practice the embodiments of the inventive subjectmatter, including making and using any devices or systems and performingany incorporated methods. The patentable scope of the inventive subjectmatter is defined by the claims, and may include other examples thatoccur to those of ordinary skill in the art. Such other examples areintended to be within the scope of the claims if they have structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal languages of the claims.

The foregoing description of certain embodiments of the inventivesubject matter will be better understood when read in conjunction withthe appended drawings. To the extent that the figures illustratediagrams of the functional blocks of various embodiments, the functionalblocks are not necessarily indicative of the division between hardwarecircuitry. Thus, for example, one or more of the functional blocks (forexample, processors or memories) may be implemented in a single piece ofhardware (for example, a general purpose signal processor,microcontroller, random access memory, hard disk, and the like).Similarly, the programs may be stand-alone programs, may be incorporatedas subroutines in an operating system, may be functions in an installedsoftware package, and the like. The various embodiments are not limitedto the arrangements and instrumentality shown in the drawings.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralof said elements or steps, unless such exclusion is explicitly stated.Furthermore, references to “one embodiment” of the inventive subjectmatter are not intended to be interpreted as excluding the existence ofadditional embodiments that also incorporate the recited features.Moreover, unless explicitly stated to the contrary, embodiments“comprising,” “including,” or “having” an element or a plurality ofelements having a particular property may include additional suchelements not having that property.

In some embodiments, code including instructions (e.g., software,firmware, middleware, etc.) may be executed on one or more processingdevices to implement one or more of the described functions orcomponents. The code and associated components (e.g., data structuresand other components used by the code or used to execute the code) maybe stored in an appropriate data memory that is readable by a processingdevice (e.g., commonly referred to as a computer-readable medium).

The components and functions described herein may be connected orcoupled in many different ways. The manner in which this is done maydepend, in part, on whether and how the components are separated fromthe other components. In some embodiments some of the connections orcouplings represented by the lead lines in the drawings may be in anintegrated circuit, on a circuit board or implemented as discrete wiresor in other ways.

What is claimed is:
 1. A method for establishing a communicationssession with an implantable medical device (IMD), the method comprising:configuring an IMD and an external device to communicate with oneanother through a protocol that utilizes a dedicated advertisementchannel; periodically transmitting, from the IMD, advertisement noticesover the dedicated advertisement channel according to the protocol, theadvertisement notices being transmitted periodically at an advertisementperiod over multiple cycles; repeatedly scanning the advertisementchannel, by the external device, for select scanning intervals in searchof the advertisement notices, the scanning operation being repeatedperiodically at a scan period over multiple cycles, wherein theadvertisement period and scan period are independent of one another suchthat the advertisement and scan periods at least partially overlapintermittently after a number of cycles; and when the external devicedetects one of the advertisement notices, establishing a communicationslink between the external device and the IMD.
 2. The method of claim 1,further comprising lengthening the scan period in order to shorten theadvertisement period.
 3. The method of claim 1, wherein the protocolincludes multiple dedicated advertisement channels and multiple datachannels.
 4. The method of claim 1, wherein the protocol constitutes aBluetooth low energy protocol.
 5. The method of claim 1, wherein theadvertisement notices are transmitted and asynchronous with respect tothe select scanning intervals, and the external device acknowledgesreceipt of the advertisement notice.
 6. The method of claim 1, whereinthe IMD enters an advertising mode, during which the transmittingoperations are performed in accordance with a Bluetooth DiscoveryService defined within the protocol.
 7. The method of claim 1, furthercomprising triggering of an advertisement mode when the IMD detects atleast one of i) a magnetic field induced upon the IMD, ii) apredetermined vibration scheme, iii) an inductive telemetry signal, oriv) a select RFID signal.
 8. The method of claim 1, wherein theadvertisement period and scan period have an asynchronous phasedrelation there between, such that a phase interval between the scanningintervals and advertisement notices changes over multiple cycles.
 9. Asystem for establishing a communication session with an implantablemedical device (IMD) comprising: an external device that is configuredto communicate over a wireless protocol that utilizes a dedicatedadvertisement channel, wherein the external device is configured torepeatedly scan the advertisement channel during a select scan intervalsuch that the scan interval is repeated periodically at a scan period;an IMD that is configured to communicate over the wireless protocol,wherein the IMD is configured to repeatedly transmit an advertisementnotice over the advertisement channel such that the advertisement noticeis repeated periodically at an advertisement period over multiplecycles; wherein the advertisement period and the scan period areindependent of one another such that the advertisement and scan periodat least partially overlap intermittently after a number of cycles; andthe external device and the IMD are configured to establish acommunication link between the IMD and the external device when theexternal device detects one of the advertisement notices.
 10. The systemof claim 9, wherein the wireless protocol utilizes multiple dedicatedadvertisement channels and multiple data channels.
 11. The system ofclaim 9, wherein the protocol constitutes a Bluetooth low energyprotocol.
 12. The system of claim 9, wherein the IMD is configured totransmit the advertisement notice asynchronous with respect to theselect scanning intervals, and the external device acknowledges receiptof the advertisement notice.
 13. The system of claim 9, wherein the IMDis configured to enter an advertisement mode, during which thetransmitting operations of the IMD and the external device areconfigured to perform in accordance with a Bluetooth Discovery Servicedefined within the wireless protocol.
 14. The system of claim 9, whereinthe IMD is configured to enter an advertisement mode when the IMD detectat least one of i) a magnetic field induced upon the IMD, ii) apredetermined vibration scheme, iii) an inductive telemetry signal, oriv) a select RFID signal.
 15. The system of claim 9, wherein theadvertisement period and scan period have an asynchronous phasedrelation there between, such that a phase interval between the scanningintervals and advertisement notices changes over multiple cycles.